1. Field of the Invention
This invention relates to a radiation image read-out apparatus for use in a radiation image recording and reproducing system. This invention particularly relates to a radiation image read-out apparatus which is made small by simplification of the internal mechanism.
2. Description of the Prior Art
When certain kinds of phosphors are exposed to a radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, they store a part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to stimulating rays such as visible light, light is emitted by the phosphor in proportion to the stored energy of the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor.
As disclosed in U.S. Pat. Nos. 4,258,264, 4,276,473, 4,315,318 and 4,387,428 and Japanese Unexamined Patent Publication No. 56(1981)-11395, it has been proposed to use a stimulable phosphor in a radiation image recording and reproducing system. Specifically, a sheet provided with a layer of the stimulable phosphor (hereinafter referred to as a stimulable phosphor sheet) is first exposed to a radiation passing through an object such as the human body to have a radiation image of the object stored thereon, and is then scanned with stimulating rays such as a laser beam which cause it to emit light in proportion to the stored radiation energy. The light emitted by the stimulable phosphor sheet upon stimulation thereof is photoelectrically detected and converted to electric image signals, and the radiation image of the object is reproduced as a visible image by use of the image signals on a recording material such as a photographic film, a display device such as a cathode ray tube (CRT), or the like.
A radiation image read-out apparatus in the aforesaid radiation image recording and reproducing system comprises a cassette holding section to which a stimulable phosphor sheet carrying a radiation image stored thereon in an external image recording apparatus is fed in the form housed in a cassette, a read-out section for scanning the stimulable phosphor sheet by stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy and photoelectrically detecting the emitted light, and a sheet conveyance means for conveying the stimulable phosphor sheet taken out of the cassette at the cassette holding section to the read-out section.
On the other hand, in the external image recording apparatus, besides the image recording on the stimulable phosphor sheet housed in the cassette, image recording may be carried out on a plurality of the stimulable phosphor sheets taken one by one out of a sheet feed magazine for continuous image recording or the like. The stimulable phosphor sheets each carrying a radiation image stored thereon are sequentially housed in a sheet housing magazine, which is then sent to a read-out apparatus for carrying out the image read-out from the housed stimulable phosphor sheets. For this purpose, in order to process also the sheet housing magazine, it is necessary for the aforesaid read-out apparatus to be provided with the aforesaid cassette holding section and a magazine holding section for releasably holding the sheet housing magazine. However, in the case where the cassette holding section and the magazine holding section are provided independently as sheet feed sections, the apparatus becomes complicated, large and expensive.